272 lines
6.7 KiB
C
272 lines
6.7 KiB
C
/*************************************************************************
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> File Name : telnetd.c
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> Author : TL Song
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> EMail : songtianlun@frytea.com
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> Created Time : Thu Feb 18 10:04:25 2021
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************************************************************************/
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#include <stdio.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <pthread.h>
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int save_fd;
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#define BUFSIZE 1024
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/*telnet_cmd:ff fb 01 ff fb 03 ff fc 1f*/
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const unsigned char cmd_telnet[9] = {0xff, 0xfb, 0x01, 0xff, 0xfb, 0x03, 0xff, 0xfc, 0x1f};
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char cmdLine[1024] = {0};
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void task_process(int sockfd);
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int telnetd(void);
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void *telnetd_pthread(void * arg);
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void *task_process_pthread(void *arg) ;
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/*启动telnet服务*/
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int telnetd_start()
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{
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#if 1
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pthread_t id;
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int i,ret;
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ret=pthread_create(&id,NULL,(void *) telnetd_pthread,NULL);
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if(ret!=0){
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printf ("Telnet: telnet_starting.......err!\n");
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return -1;
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}
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#else
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int pid;
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int status;
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if(pid=fork()) {
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//exit(0); //是父进程，结束父进程
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waitpid(-1, &status, WNOHANG | WUNTRACED | WCONTINUED);
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return 0;
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} else if(pid < 0) {
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return -1;//exit(1); //fork失败，退出
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}
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printf("Telnet: telnet_starting.......\n");
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telnetd();
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#endif
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}
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/*telnet 主服务任务*/
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int main(int argc, char *argv[])
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{
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return telnetd_start();
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}
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int telnetd(void)
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{
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pid_t fpid;
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int status;
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int server_sockfd;//服务器端套接字
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int client_sockfd;//客户端套接字
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int len;
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struct sockaddr_in server_addr; //服务器网络地址结构体
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struct sockaddr_in remote_addr; //客户端网络地址结构体
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int sin_size;
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memset(&server_addr,0,sizeof(server_addr)); //数据初始化--清零
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server_addr.sin_family=AF_INET; //设置为IP通信
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server_addr.sin_addr.s_addr=htonl(INADDR_ANY);//服务器IP地址--允许连接到所有本地地址上
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server_addr.sin_port=htons(23); //服务器telnet端口号
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//init_telnetd();
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/*创建服务器端套接字--IPv4协议，面向连接通信，TCP协议*/
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if((server_sockfd=socket(AF_INET,SOCK_STREAM,0))<0)
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{
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perror("socket");
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return -1;
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}
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/*将套接字绑定到服务器的网络地址上*/
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if (bind(server_sockfd,(struct sockaddr *)&server_addr,sizeof(struct sockaddr))<0)
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{
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perror("bind");
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return -1;
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}
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/*监听连接请求*/
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listen(server_sockfd,1);
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printf("Telnet: listening for telnet requests....\n");
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sin_size=sizeof(struct sockaddr_in);
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while(1) {
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/*等待客户端连接请求到达*/
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if((client_sockfd=accept(server_sockfd,(struct sockaddr *)&remote_addr,&sin_size))<0)
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{
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perror("accept");
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return 1;
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}
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//printf("accept client %s\n",inet_ntoa(remote_addr.sin_addr));
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#if 0
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fpid = fork();
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if (fpid < 0) {
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perror("call fork() err!\n");
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exit(1);
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} else if (fpid == 0) {
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task_process(client_sockfd);
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close(client_sockfd);
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exit(0);
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} else {
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waitpid(-1, &status, WNOHANG | WUNTRACED | WCONTINUED);
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}
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#else
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pthread_t id;
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int i,ret;
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ret=pthread_create(&id,NULL,(void *) task_process_pthread,(void *)client_sockfd);
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if(ret!=0){
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printf ("Telnet: telnet_starting.......err!\n");
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return -1;
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}
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pthread_join(id,NULL);
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#endif
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}
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close(client_sockfd);
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close(server_sockfd);
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return 0;
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}
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void * telnetd_pthread(void *arg)
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{
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telnetd();
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}
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/*发送telnet协议命令*/
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int send_telnet_cmd(int fd)
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{
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return write(fd, cmd_telnet, sizeof(cmd_telnet));
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}
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/*读取命令字符串*/
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int read_cmdline(int sockfd, char *cmdLine, int size)
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{
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int ret, rev_count = 0;
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char *buf = NULL;
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buf = cmdLine;
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while(1 == (ret = read(sockfd, buf, 1))) {
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rev_count++;
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if(rev_count > BUFSIZE - 2) {
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return rev_count;
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}
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if(*buf == '\n') {
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return rev_count;
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}
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buf++;
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}
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return ret;
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}
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/*输出重定向*/
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int ioStdSet(int src_fd, int dest_fd, int *save_fd)
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{
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*save_fd = dup(dest_fd);
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dup2(src_fd, dest_fd);
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//close(src_fd);
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return *save_fd;
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}
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/*恢复输出重定向*/
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void recoverIoStdSet(int src_fd, int dest_fd)
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{
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dup2(src_fd, dest_fd);
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close(src_fd);
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}
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/*解析字符串*/
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int cmd_analyze(char *cmd)
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{
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unsigned char *ptr = NULL;
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unsigned char *ptr_tmp;
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if(strlen(cmd) < 12 || strlen(cmd) > 48) {
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return -1;
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}
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/*去除多余的换行符及其他多余字符*/
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while((ptr = strstr(cmd, "\r")) != 0 ) {
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while(*ptr != 0) {
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*ptr = *(ptr+1);
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ptr++;
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}
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}
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while((ptr = strstr(cmd, "\n")) != 0 ) {
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while(*ptr != 0) {
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*ptr = *(ptr+1);
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ptr++;
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}
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}
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#if 1
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ptr = cmd;
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while((!((*ptr > 'a' && *ptr < 'z') || (*ptr > 'A' && *ptr < 'Z') || (*ptr > '0' && *ptr < '9'))) && (*ptr != 0)) {
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ptr_tmp = ptr;
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while(*ptr_tmp != 0) {
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*ptr_tmp = *(ptr_tmp+1);
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ptr_tmp++;
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}
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}
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#endif
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if(strlen(cmd) < 12 || strlen(cmd) > 48) {
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return -1;
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}
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return 0;
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}
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/*执行命令并回显到telnet终端*/
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int cmd_process(int fd, char *cmdLine)
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{
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ioStdSet(fd, 1, &save_fd); /*标准输出重定向*/
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/*这里添加命令处理函数*/
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/*示例*/
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printf("Welcome to Telnet server.[%s]\n",cmdLine);
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recoverIoStdSet(save_fd, 1); /*恢复输出重定向*/
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return 0;
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}
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/*telnet交互处理函数*/
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void task_process(int sockfd)
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{
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char cmdLine[BUFSIZE]={0};
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int count = 0;
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int i=0,tmp = 0;
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int ret;
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while(1) {
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send_telnet_cmd(sockfd);
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ioStdSet(sockfd, 1, &save_fd);
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printf("\r\r\nlinux>");
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recoverIoStdSet(save_fd, 1);
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memset(cmdLine, 0, sizeof(cmdLine));
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count = read_cmdline(sockfd, cmdLine, BUFSIZE);
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if(count <= 0) {
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//perror("read err");
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//exit(1);对方断开连接，返回
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return ;
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}
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ret = cmd_analyze(cmdLine);
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//printf("[%s,%d]rev count:%d,buf:%s\n",__FUNCTION__,__LINE__,count, cmdLine);
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if(ret == 0) {
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cmd_process(sockfd, cmdLine);
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}
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}
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}
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void *task_process_pthread(void *arg)
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{
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int sockfd;
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sockfd = (int) arg;
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task_process(sockfd);
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pthread_exit((void *)1);
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} |